/**
 * Copyright (C) 2010-2013 Alibaba Group Holding Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.rocketmq.client.impl;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

import com.alibaba.rocketmq.client.ClientConfig;
import com.alibaba.rocketmq.client.impl.factory.MQClientInstance;
import com.alibaba.rocketmq.remoting.RPCHook;

/**
 * @author shijia.wxr<vintage.wang@gmail.com>
 * @since 2013-7-24
 */
public class MQClientManager {
	private static MQClientManager instance = new MQClientManager();
	private AtomicInteger factoryIndexGenerator = new AtomicInteger();
	private ConcurrentHashMap<String/* clientId */, MQClientInstance> factoryTable = new ConcurrentHashMap<String, MQClientInstance>();

	private MQClientManager() {

	}

	public static MQClientManager getInstance() {
		return instance;
	}

	public MQClientInstance getAndCreateMQClientInstance(final ClientConfig clientConfig, RPCHook rpcHook) {
		// 5、构建该Producer的ClientID，等于IP地址@instanceName；
		String clientId = clientConfig.buildMQClientId();
		// 先检查单例对象MQClientManager的factoryTable:ConcurrentHashMap<String/* clientId */, MQClientInstance>变量中是否存在该ClientID的对象，
		MQClientInstance instance = this.factoryTable.get(clientId);
		if (null == instance) {
			// ******************** 6、若不存在，则创建MQClientInstance对象，***************************
			instance = new MQClientInstance(clientConfig.cloneClientConfig(), this.factoryIndexGenerator.getAndIncrement(), clientId, rpcHook);
			// 并以该ClientID为key值将新创建的MQClientInstance对象存入并返回，将返回的MQClientInstance对象赋值给DefaultMQProducerImpl.mQClientFactory变量
			// 说明一个IP客户端下面的应用，只有在启动多个进程的情况下才会创建多个MQClientInstance对象；
			MQClientInstance prev = this.factoryTable.putIfAbsent(clientId, instance);
			if (prev != null) {
				instance = prev;
			} else {
				// TODO log
			}
		}
		// 若存在则直接返回该MQClientInstance对象
		return instance;
	}

	public MQClientInstance getAndCreateMQClientInstance(final ClientConfig clientConfig) {
		return getAndCreateMQClientInstance(clientConfig, null);
	}

	public void removeClientFactory(final String clientId) {
		this.factoryTable.remove(clientId);
	}
}
